Conformationally rigid bicyclic and adamantane derivatives useful as alpha2-adrenergic blocking agents

ABSTRACT

A compound of formula I  
                 
 
     in which: ring A is one of the five alternative multi-cyclic rings as shown wherein a dotted line adjacent to a bond indicates that a single bond or a double bond may be present at that position; X is nitrogen, oxygen or sulfur; R is hydrogen, lower straight or branched chain alkyl of 1 to 6 carbon atoms, or lower straight or branched chain alkenyl of 2 to 6 carbon atoms, a cycloaliphatic ring of 3 to 6 carbon atoms, phenyl optionally mono- or di-substituted with hydroxy, halogen, alkyl of 1 to 3 carbon atoms or alkoxy of 1 to 2 carbon atoms, or methylenedioxyphenyl; or a stereoisomer, or a pharmaceutically acceptable salt thereof.  
     These compounds have α 2  receptor blocking activity and hence find use in the treatment or palliation of elevated intraocular pressure, non insulin-dependent diabetes, male impotence and obesity.

FIELD OF THE INVENTION

[0001] The present invention relates to aliphatic bridged-cycliccompounds with 2-amino-imidazoline, 2-amino-oxazoline or2-amino-thiazoline substituents. More particularly, the inventionrelates to such compounds which are selective in blocking the α₂adrenoreceptor. These compounds find use in the treatment of conditionswhich are responsive to regulation of α₂-receptor responses, suchactivities include, for example, treatment of depression, palliation ofnon insulin-dependent diabetes, alleviation of male impotence, loweringof intraocular pressure (which is useful in treating e.g. glaucoma) andstimulation of weight loss.

BACKGROUND OF THE INVENTION

[0002] Adrenergic agents, and particularly agents affective on α₂adrenergic receptors are known in the art. For example, U.S. Pat. No.5,091,528 describes 6- or 7-(2-imino-2-imidazoline)-1,2-benzoxazine as aadrenergic agents. Published European patent application 0 251 453describes certain cyclohexyl substituted amino-dihydro-oxazoles,-thiazoles and -imidazoles as α₂ agents. U.S. Pat. No. 3,598,833describes 2-cycloalkylamino oxazolines having local anesthetic,sedative, vasoconstrictor, mucous membrane de-swelling, blood pressuredepressant and gastric fluid secretory inhibition effects. FurtherUnited States and foreign patents and scientific publications whichpertain to substituted amino-oxazoline, imidazolines and thiazolines areas follows:

[0003] U.S. Pat. No. 4,587,257 [2-trisubstituted phenylimino)imidazoline compounds capable of controlling ocular bleeding];

[0004] U.S. Pat. No. 3,636,219 [2-(substituted-phenylamino)-thiazolinesand imidazolines having anticholinergic activity];

[0005] U.S. Pat. No. 3,453,284 [2-substituted anilino)-2-oxazolines;

[0006] U.S. Pat. No. 3,432,600 [partially reduced 2-(naphthylamino)oxazolines and 2-(indanylamino) oxazolines;

[0007] U.S. Pat. No. 3,679,798 [compositions comprisingarylaminooxazolines and an anticholinergic agent];

[0008] U.S. Pat. No. 3,624,092 [amino-oxazolines useful as centralnervous system depressants];

[0009] U.S. Pat. No. 2,876,232 [2-(9-fluorenylamino)-oxazolines), andGerman Patent nos. 1,191,381 and 1,195,323 and European PatentApplication no 87304019.0;

[0010] U.S. Pat. No. 4,515,800 [2-(trisubstituted phenylimino)imidazoline compounds, also known as2-(trisubstituted-anilino)-1,3-diazacyclopentene-(2) compounds, fortreatment of glaucoma];

[0011] U.S. Pat. No. 5,066,664[2-(hydroxy-2-alkylphenylamino)-oxazolines and thiazolines as antiglaucoma and vasoconstrictive agents].

[0012] Chapleo et al. [Journal of Medicinal Chemistry 1989, 32 1627-30]describe heteroaromatic analogs of clonidine as partial agonists of α₂adrenoceptors.

[0013] Poos, et al. [Journal of Organic Chemistry, 1961, 26, 4898-904.]reported the syntheses of isomeric forms of 2-amino-3-phenylnorbornanes,and that the endo-phenyl-exo-amino compounds demonstrated a biphasiceffect on blood pressure. U.S. Pat. No. 3,514,486 to Hartzler disclosesmaking 3-isopropyl-2-norbornanamine and reports that they have usefulantihypertensive activity.

[0014] Additionally, commonly assigned co-pending applications Ser. Nos.08/186,406 and 08/185,653 disclose alpha-substituted derivatives ofaromatic 2-amino-imidazoles and methods of using the same as α_(2A)selective agonists.

[0015] The background of the division of adrenoceptors into differingcategories can be briefly described as follows. Historically,adrenoceptors were first divided into α and β subtypes by Ahlquist in1948. This division was based on pharmacological characteristics. Later,β-adrenoceptors were subdivided into β₁ and β₂ subtypes, again based ona pharmacological definition by comparison of the relative potencies of12 agonists. The α-adrenoceptors were also subdivided into α₁ and α₂subtypes, initially based on a presumed localization of α₁ receptorspostsynaptically and α₂ presynaptically. Now, however, this physiologicdivision is no longer used and it is generally accepted that the mostuseful way to subdivide the a-adrenoceptors is based on pharmacology,using affinities for the a-antagonists yohimbine and prazosin. At α₁receptors, prazosin is more potent than yohimbine, whereas at α₂receptors, yohimbine is more potent than prazosin. More recently the α₁and α₂ receptors have been further subdivided into subtypes such asα_(1A), α_(1B), α_(1C), α_(2A), α_(2B) and α_(2C).

[0016] The term agonist refers to a class of compounds which bind withsome affinity to and activate a particular type of receptor. Activationrefers to what could be considered analogous to flipping on a switch,i.e. the receptor is induced to initiate some kind of action like aphysiologic response or a chain of biochemical events. The termantagonist (or receptor blocker) refers to a class of compounds whichbind to a receptor with some affinity, but are unable to activate thereceptor to provide an effect. The antagonist can be compared to a keywhich is able to slide into a lock, but is unable to turn in the lock toopen it.

[0017] Some examples of alpha₂ (α₂) adrenergic receptor blockingcompounds known in the art are:

[0018] Idazoxan is classified as a selective a₂ antagonist, and has beenstudied in combination with tyrosine as an antidepressant and incombination with D₂ dopamine receptor antagonists as an antipsychoticagent.1,2,3,4-tetrahydro-6hydroxy-1-((N-methyl-amino)-methyl-N-phenylethyl)naphthalenehydrochloride (A-75169) lowers intraocular pressure in mammals.

[0019] The receptor affinity of candidate compounds can be determined byradioligand binding competition studies. Radioligand binding competitionstudies assess the affinity of a compound by measuring its ability todisplace a radioligand of known affinity.

[0020] As described above, an agonist is defined as a compound thatbinds to and activates a receptor response. An antagonist binds to, butdoes not activate a response by, the receptor. The measure of activationcaused by a bound molecule is said to be its efficacy. Functionalexperiments are designed to determine whether, after binding, a testcompound elicits a biochemical effect, or rather binds without causingthe receptor to respond. An antagonist, if of sufficient bindingaffinity, can be used to block the binding of endogenous molecules inthe body which activate a receptor, and thereby prevent its activation.Antagonists can find therapeutic use by blocking the binding of anoversupply of an endogenous receptor activator or the over expression ofa receptor effect. Owing to the intricacy of the interactions between agiven binding molecule and the conformation and function of the receptoritself, partial agonists and partial antagonists are also known inreceptor pharmacology.

SUMMARY OF THE INVENTION

[0021] The present invention concerns novel compounds of the formula I,

[0022] in which: ring A is any of the five alternative multi-cyclicrings shown, X is nitrogen, oxygen or sulfur and R is hydrogen, straightor branched chain alkyl of 1 to 6 carbon atoms, or straight or branchedchain alkenyl of 2 to 6 carbon atoms, a cycloaliphatic ring of 3 to 6carbon atoms, phenyl optionally mono- or di-substituted with hydroxy,halogen, alkyl of 1 to 3 carbon atoms or alkoxy of 1 to 2 carbon atoms,or methylenedioxyphenyl. In the drawing of chemical structures as shownabove, the intersection of two or more lines indicates a carbon atom, asingle line indicates a single bond, and a double line a double bond,and a dotted line adjacent a single line indicates either a single ordouble bond. The chemical nomenclature for the rings shown above fromleft to right in descending order is norbornane (orbicyclo[2.2.1]heptane); bornane (or1,7,7-trimethyl-bicyclo[2.2.1]heptane); 7-oxa-bicyclo[2.2.1]heptane;bicyclo[2.2.2]octane and adamantane (or tricyclo[3.3.1.13,7]decane). Thewavy lines across a bond indicate that the bond attaches to either the Ror 2-amino-heterocyclic moieties. Any stereoisomers and diastereomerswhich are available by bonding the substituents R and the2-amino-heteroazole moieties to the available valences of theabove-indicated carbons on the rings are contemplated by the invention,as well as the pharmaceutically acceptable salts.

[0023] Another aspect of the invention concerns the method of use ofthese compounds in blocking or antagonizing α2 receptor function.

[0024] Other aspects of the invention relate to pharmaceuticalcompositions containing the compounds of the invention in admixture withone or more pharmaceutically acceptable, non-toxic carriers, and tomethods pertaining to their use.

DETAILED DESCRIPTION OF THE INVENTION

[0025] Definitions

[0026] As used herein:

[0027] The terms “ester” and “amide” refer to and cover any compoundfalling within the definition of those terms as classically used inorganic chemistry.

[0028] The term “alkyl” refers to and includes normal and branched chainalkyl groups as well as cycloalkyl groups. The term “lower alkyl”,unless specifically stated otherwise, includes normal alkyl of 1 to 6carbons, branched-chain alkyl of 3 to 6 carbons and cyclo-groups having3 to 6 carbon atoms. Similarly, the terms “alkenyl” and “alkynyl”include normal and branched chain as well as cyclo-alkenyl and alkynylgroups, respectively, having 2 to 6 carbons when the chains are normal,and 3 to 6 carbons when the chains are branched or cyclic.

[0029] The terms endo and exo are used in describing a substituent inspatial relation to its connection to a bridged ring and refer to theposition of the substituent as either “inside” or “outside” the ring.For the bicycloheptane compounds, endo refers to a substituent attachedto the ring by a bond that points down and below the general plane ofthe six membered ring, and exo refers to a substituent attached to thering by a bond that points out from and above the general plane of thesix membered ring.

[0030] The terms cis and trans are also used in describing the relativestereochemistry of the substituents of the present invention. Since thecarbon atoms at positions 2 and 3 in the norbornane andbicyclo[2.2.2]octane rings are rigidly fixed by the bicyclic ringstructure there is no bond rotation or alternative conformation of thering system. Thus, the bond between carbon atoms 2 and 3 can be likenedto a double bond in that respect, and so relative stereochemistry can bedescribed with cis indicating that the substituents are located on thesame side of the bond, and trans indicating that the substituents arelocated in positions opposite one another across the bond.

[0031] Pharmaceutically acceptable salts of the compounds of formula Iare also within the scope of the present invention. Pharmaceuticallyacceptable acid addition salts of the compounds of the invention arethose formed from acids which provide pharmaceutically acceptableanions, such as the hydrochloride, hydrobromide, hydroiodide, sulfate,bisulfate, phosphate or acid phosphate, acetate, maleate, fumarate,oxalate, lactate, tartrate, citrate, gluconate, saccharate, ortoluenesulfonate salts. A pharmaceutically acceptable salt may be anysalt which retains the activity of the parent compound and does notimpart any deleterious or untoward effect on the subject to which it isadministered and by the context in which it is administered.

[0032] Organic amine salts may be made with amines, particularlyammonium salts such as mono-, di- and trialkyl amines or ethanol amines.Salts may also be formed with caffeine, tromethamine, and similarmolecules. Where there is a nitrogen sufficiently basic as to be capableof forming acid addition salts such may be formed with any inorganic ororganic acids or alkylating agent such as methyl iodide. Any of a numberof simple organic acids such as mono-, di-, or tri-acid may also beused. A pharmaceutically acceptable salt may be prepared for anycompound of the invention having a functionality capable of forming sucha salt, e.g., an acid salt of an amine functionality.

[0033] Utility and Dosage Forms

[0034] The compounds of formula I and pharmaceutically acceptable acidaddition salts thereof have been found to possess valuable pharmacologicproperties in the central nervous system and, in particular, have beenshown to block (antagonize) α₂ receptors in standard laboratory tests.Accordingly, these compounds and pharmaceutically acceptablecompositions containing them are useful in reduction or maintenance ofthe intraocular pressure in at least one eye of a mammal and inregulation of other physiologic phenomena related to α₂ receptors. Suchphysiologic activities include for example: alleviation, prevention orinhibition of depression in mammals; reduction in the severity ofdiabetes; alleviation of male impotence; and stimulation of weight loss.

[0035] In applying the compounds of the invention to treatment ofdiseases or disorders of the eye which are associated with an abnormallyhigh intraocular pressure, administration may be achieved by anypharmaceutically acceptable mode of administration which providesadequate local concentrations to provide the desired response. Theseinclude direct administration to the eye via drops and controlledrelease inserts or implants, as well as systemic administration asdescribed below.

[0036] Drops and solutions applied directly to the eye are typicallysterilized aqueous solutions containing 0.001% to 10%, most preferably0.005% to 1% of the active ingredient, along with suitable buffer,stabilizer, and preservative. The total concentration of solutes shouldbe such that, if possible, the resultant solution is isotonic with thelachrymal fluid and has a pH in the range of 6-8. Typical sterilizingagents are thimerosal, chlorobutanol, phenyl mercuric nitrate andbenzalkonium chloride. Typical buffers are, for example, citrate,phosphate, borate or tromethamine; suitable stabilizers include glycerinand polysorbate 80. The aqueous solutions are formulated by simplydissolving the solutes in a suitable quantity of water, adjusting the pHwith suitable acid or base to a pH of about 6.8 to 8, making a finalvolume adjustment with additional water and sterilizing the resultantsolution.

[0037] The dosage level of the resulting composition will, of course,depend on the concentration of the drops, the condition of the subjectand the individual magnitude of response to treatment. However, atypical ocular composition could be administered at the rate of about 2to 10 drops per day per eye of a 0.1% solution of active ingredient.

[0038] The compounds of the present invention, when administered forconditions which are regulated by the central nervous system (CNS), canbe by any of the accepted modes of administration for agents whichrelieve depression or affect the CNS including oral, parenteral, rectal,and otherwise systemic routes of administration. Any pharmaceuticallyacceptable mode of administration can be used, including solid,semi-solid, or liquid dosage forms, such as for example, tablets,suppositories, pills, capsules, powders, liquids suspensions, or thelike, preferably in unit dosage form suitable to single administrationof precise dosages, or in sustained or controlled release forms for theprolonged administration of the compound at a predetermined rate. Thecompositions will typically include a conventional pharmaceuticalcarrier or excipient and an active compound of formula I or thepharmaceutically acceptable salts thereof and, in addition, may includeother medicinal agents, pharmaceutical agents, carriers, adjuvants, etc.

[0039] The amount of active compound administered will course bedependent of the subject being treated, the severity of the affliction,the manner of administration and the judgment of the prescribingphysician. However, an effective dosage is in the range of 0.01-1mg/kg/day, preferably 0.1-0.5 mg/kg/day. For an average human of about70 kg, this would amount to 0.7-70 mg/day.

[0040] For solid compositions, conventional non-toxic carriers include,for example mannitol, lactose, starch, magnesium stearate, sodiumsaccharin, talcum, cellulose, glucose, sucrose, magnesium carbonate, andthe like may be used. The active compound as defined above may beformulated as suppositories using, for example, polyalkylene glycols,for example, propylene glycol as a carrier. Liquid pharmaceuticallyadministerable compositions can, for example, be prepared by dissolving,dispersing, etc. an active compound as defined above and optionalpharmaceutical adjuvants in a carrier, such as, for example, water,saline, aqueous dextrose, glycerol, ethanol, and the like to therebyform a solution or suspension. If desired, the pharmaceuticalcomposition to be administered may also contain minor amounts of nontoxic auxiliary pH buffering agents and the like, for example, sodiumacetate, sorbitan monolaurate, triethanolamine oleate, etc. Actualmethods of preparing such dosage forms are known, or will be apparent.to those skilled in this art; for example, see Remington'sPharmaceutical Sciences, Mack Publishing Company, Easton, Pa., 15thEdition, 1975. The composition or formulation to be administered will,in any event, contain a quantity of the active compound in an amounteffective to alleviate the symptoms of the subject being treated.

[0041] Dosage forms or composition containing active ingredient offormula I or its salts in the range of 0.25 to 95% with the balance madeup from non-toxic carrier may be prepared.

[0042] For oral administration, a pharmaceutically acceptable non-toxiccomposition is formed by the incorporation of any of the normallyemployed excipients, and may contain 1% -95% active ingredient,preferably 5%-50%.

[0043] Parenteral administration is generally characterized byinjection, whether subcutaneously, intramuscularly, or intravenously.Injectables can be prepared in conventional forms, either as liquidsolutions or suspension, solid forms suitable for solution or suspensionin liquid prior to injection, or as emulsions. Suitable excipientsinclude, for example, water, saline, aqueous dextrose, glycerol, ethanolor the like. In addition, if desired, the pharmaceutical compositionsmay also contain minor amounts of non-toxic substances such as wettingor emulsifying agents, auxiliary pH buffering agents and the like, forexample, sodium acetate, sorbitan monolaurate, triethanolamine oleate,etc.

[0044] The percentage of active compound contained in such parenteralcompositions is highly dependent on the specific nature thereof, as wellas the activity of the compound and the needs of the subject. However,percentages of active ingredient of 0.1% to 10% in solution areemployable, and will be higher if the composition is a solid which willbe subsequently diluted to the above percentages. Preferably thecomposition will comprise 0.2-2% of the active agent in solution.

[0045] Preferred Embodiments

[0046] Among the family of compounds of the present invention, apreferred group includes compounds of formula I wherein X is oxygen,i.e. compounds where the oxazoline ring constitutes the heterocycle.

[0047] A second preferred group of compounds of the invention are thosethat incorporate the bicyclo[2.2.1]heptane group in their structure asthe ring A group.

[0048] Within either of the two preceding preferred groups, a still morepreferred embodiment is of compounds which have a hydrogen atom or anaromatic group at the position represented by R.

[0049] Methods of Preparation

[0050] As illustrated by Scheme I below, treatment of an alkynyl acidwith diazomethane in ether afforded the corresponding ester. The esterand cyclopentadiene were warmed at 175° C. for 40 hours to form thecycloadduct. This adduct was unstable to SiO₂ chromatography and wasbest purified using a Kugelrohr distillation.

[0051] The double bonds in the cycloadduct were immediately saturated bytreatment with H₂ and Pd/C at one atmosphere. Conversion of the esterinto an amine was accomplished by conversion to the carboxylic acidfollowed by a Curtius reaction. Thus, the acid was activated bytreatment with isobutylchloroformate. The acyl azide was formed bytreatment with sodium azide. Elimination of nitrogen and formation of abenzyl carbamate occurred when the azide was warmed in toluene in thepresence of benzyl alcohol. The amine was liberated upon treatment withH₂ and Pd/C at one atmosphere. Oxazoline synthesis was accomplishedunder standard conditions: treatment first with chloroethylisocyanateand then aqueous NaHCO₃ solution.

[0052] endo, exo Relative stereochemistry

[0053] Preparation of b-nitrostyrene was accomplished according to theOrganic Syntheses method. Treatment of a methanol solution ofbenzaldehyde with nitromethane (100 mol.-%) in the presence of sodiumhydroxide (105 mol.-%) afforded the nitro alcohol. Dehydration of thealcohol was effected by treatment with aqueous hydrochloric acid (5M).

[0054] The nitrostyrene of 3,4-dihydroxybenzaldehyde was obtained bytreating piperonal (3,4-methylenedioxybenzaldehyde) in a similar fashionto that reported for b-nitrostyrene. The acetal proved stable to theaqueous acid required for dehydration.

[0055] Construction of the bicyclo[2.2.1]heptane skeleton was carriedout in two steps. The Diels-Alder reaction was conducted by warming thenitrostyrene with cyclopentadiene (110 mol.-%) neat (b-nitrostyrene is alow melting material) or in 1,2-dichloroethane (1M in nitroolefin). TheDiels-Alder reaction proceeds in approximately a 3:1 endo nitro: exonitro ratio. Both the ratio and relative stereochemistry wasdemonstrated through X-ray analysis. Reduction of both the nitro groupand the olefin was carried under an atmosphere of hydrogen in thepresence of 10 weight-% palladium on charcoal (10%). Separation ofisomers was conveniently carried out at this stage using flashchromatography.

[0056] Oxazoline synthesis was conducted under standard conditions. Theamine was first converted to the chloroethylurea by treatment withchloroethylisocyanate. Warming the chloroethylurea in the presence ofsodium bicarbonate afforded the oxazolines. This effort is summarized inScheme II. Thiazolines and imidazolines were also prepared understandard conditions. Treatment of amines with chloroethylisothiocyanateaffords thiazolines directly while treatment with imidazoline-2-sulfonicacid affords the corresponding imidazolines in a single step.

[0057] Reagents and Conditions: i. CH3NO2, KOH, MeOH; ii. HCl; iii.cyclopentadiene, neat or 1M in dichloroethane; iv. H2, 10 Pd on C; v.chloroethylisocyanate; vi. NaHCO3 [X=O]; vii. chloroethylisothiocyanate[X=S]; viii. imidazoline-2-sulfonic acid [X=NH].

[0058] Synthesis of oxabicyclo[2.2.1]heptane derivatives of the presentinvention can also be prepared by Diels Alder reactions following meanswell known in the art. Grieco, Zelle, Lis and Finn in Journal of theAmerican Chemical Society. 105 1403-4 (1985) report means of makingsuitably derivatized oxabicyclo[2.2.1]heptane andoxabicyclo[2.2.1]heptene compounds which can be elaborated intocompounds of the present invention. This can be accomplished by thesynthetic steps which follow the Diels Alder cycloaddition in Scheme 1using the 2-carbomethoxy-bicyclo[2.2.1]hept-2-ene intermediate of thereference, or if the nitro functionality of other of the Grieco et al.compounds are employed, according to the steps iv, v, vi (or vii orviii) in Scheme 2. Another journal article by Jarvest and Readshawdisclose advantageous conditions for Diels-Alder cyclization ofderivatized furans and cyanoacrylate to yield2-cyano-5-substituted-bicyclo[2.2.1]heptanes. These articles areincorporated by reference herein in their entirety.

[0059] The invention is further illustrated by the followingnon-limiting examples which are illustrative of a specific mode ofpracticing the invention and are not intended as limiting the scope ofthe appended claims.

EXAMPLE 1 2-Hydroxy-1-nitrohexane

[0060] Pentanal (49.6 ml, 464 mmol) was stirred in a solution ofnitromethane (276 ml, 5108 mmol). To the reaction methanolic KOH (3N)was added dropwise to pH 8. The reaction was stirred at room temperatureovernight. The solution contained trace amounts of insoluble dark brownmaterial. The solution was washed with H₂O and extracted intodichloromethane; concentration of the solvent gave clean product (II) in96% yield, (56.58 g).

EXAMPLE 2 1-Nitrohex-1-ene

[0061] The nitroalcohol (1) (2.0 g, 13.6 mmol) was dissolved indichloromethane and treated at 0° C. for 30 minutes by dropwise additionwith methanesulfonyl chloride (1.6 g, 13.6 mmol). Triethylamine (2.75 g,27.2 mmol) was then added dropwise and stirred for an additional hour at0° C. The product was washed with 1M H₃PO₄ and then with saturatedNaHCO₃ and extracted with dichloromethane. Concentration of the solventgave the olefin in 80% yield (3.03 g).

EXAMPLE 3 Trans-2-nitro-3-butyl bicyclo[2.2.1]heptane

[0062] The nitroolefin (2) (3.00 g, 19.3 mmol) was dissolved in 20 ml ofdichloromethane and then freshly cracked cyclopentadiene (6.49, 96.6mmol) was added and bubbled with argon for 15 minutes. This was added toa sealable tube and, once sealed was placed in an oil bath at 90° C.overnight. The reaction went to completion. Excess cyclopentadiene wasremoved by Kugelrohr distillation. The resultant product was obtained in60% yield (3.53 g).

EXAMPLE 4 Trans 2-(3-butyl-bicyclo[2.2.1]heptyl)amine

[0063] The cycloadduct (3) (2.53 g, 13.0 mmol) was dissolved in methanol(25 ml) and bubbled with Ar. To this was added 10% palladium on carbon(500 mg). This vessel containing this mixture was put on a Parrapparatus for hydrogenation at 50 psi overnight. The reduced materialwas filtered through celite and the solvent was concentrated. Theresidue was dissolved in 1M H₃PO₄ and washed with dichloromethane. Theaqueous layer was basified with 25% NaOH to a pH of ca. 13. This wasextracted with dichloromethane three times. The organic layers werecombined and concentrated to give the product in 86% yield (1.86 g).

EXAMPLE 5A Trans 2-(3-butyl bicyclo[2.2.1]heptyl)amino-oxazoline

[0064] The amine (4) (200 mg, 1.20 mmol) was dissolved in THF (5 ml). Tothis was added chloroethylisocyanate (0.122 ml, 1.40 mmol) dropwise andstirred at room temperature for two hours. The reaction mixture waspoured into 1M H₃PO₄ and ice (1:1) to quench the reaction. This was thenextracted with dichloromethane and concentrated to give the urea. Theurea was treated with methanol (6 ml), water (6 ml) and NaHCO₃ (202 mg,2.4 mmol). This mixture was refluxed at 80° C. for 2 hours. The reactionwas quenched with saturated NaHCO₃ and extracted with dichloromethane.The organic layers were combined and concentrated to give desiredproduct (270 mg). Column chromatography with 5% MeOH saturated with NH₃in dichloromethane gave the desired product in 60% yield (155 mg).

[0065]¹H NMR(CDCl3): 0.70-1.70(M,16H), 1.9(d, 1H), 2.5(5, 1H), 3.4(S1H)3.75(t,2H), 4.1(5,1H), 4.25(t,2H).

[0066] Elemental analysis:theoretical—C, 71.14%; H, 10.23%; N, 11.86%;found—C, 70.8%; H, 10.20%; N, 11.60%.

[0067] 5B.

Trans 2-(3-butyl-bicyclo[2.2.1]heptyl)aminothiazoline

[0068] The amine (4) (200 mg, 1.20 mmol) in THF (5 ml) was treated withchloroethylisothiocyanate dropwise at 0° C. for 3 hours. The reactionmixture was poured into 1M H₃PO₄. The aqueous layer was extracted withdichloromethane and then basified with 25% NaOH to pH 13. The aqueouslayer was then extracted with dichloromethane three times. The organiclayers were combined and concentrated to give the product in 11.6% yield(35 mg).

[0069]¹H NMR (CDCl3): 0.85 (t, 3H), 1.1-1.7(M, 13H), 1.95 (d,1H), 2.5(S, 1H) 3.3 (t,2H), 3.5 (S,1H), 4.0 (t, 2H).

[0070]¹³C NMR C (CD₃OD): d 14.0, 21.0, 23.0, 30.0, 30.5, 35.0, 35.2,35.3, 40.5, 41.5, 51.5, 64.0.

[0071] Elemental analysis: theoretical—C, 66.63%; H, 9.59%; N, 11.10%;found—C, 66.40%; H, 9.52%; N, 11.0%.

[0072] 5C.

Trans 2-(3-butyl-bicyclo[2.2.1]heptyl)aminoimidazoline

[0073] An acetonitrile (2.4 ml) suspension of the amine (4) (200 mg,1.20 mmol) with triethylamine (0.184 ml, 1.32 mmol) and then withimidazoline-2-sulfonic acid (198 mg, 1.32 mmol). The solution wasrefluxed for 2 hours. Aqueous workup with 1 M H₃PO₄ and then basifyingaqueous layer to pH 13 and extraction with dichloromethane gave thedesired product. The HCl salt was prepared from HCl/ether in methanolwhich gave a yield of 20% (60 mg).

[0074]¹H NMR (CDCl3): 0.70-1.70 (M, 16H), 2.0 (d, 1H), 2.6 (S,1H),3.4(S,1H) 3.65(S,4H).

[0075]¹³C NMR (CHCl₃): d 22.9, 27.8, 27.89, 28.05, 31.83, 32.29, 33.41,37.34, 39.89, 42.53, 42.89, 44.06, 44.54, 57.9, 61.6, 95.6, 161.02.

EXAMPLE 6A exo-[2.2.1]bicycloheptyl-2-amino-oxazoline

[0076] A THF solution containing the exo-norbornylamine was cooled to 0°C. under a nitrogen atmosphere and was treated withchloroethylisocyanate. The magentically mixed solution was allowed towarm to r.t. over 1 h and then stirred an additional 1 h at r.t. Afterextraction from 1 M H₃PO₄ (20 mL; 3×15 mL CH₂Cl₂ extraction) and dryingover Na₂SO₄, the white solid recovered after concentration was warmed atreflux in aqueous MeOH containing NaHCO₃. After extraction from 0.5NNaOH, drying (Na2SO4) concentration and chromatography (eluent: 5%NH₃-saturated MeOH in CH₂Cl₂; 230-400 mesh SiO₂; eluate collected in 10mL fractions). Fractions 10-20 afforded 350 mg of the agent (65%).Recrystallization was accomplished using pure hexane.

[0077] mp 115-117° C.

[0078]¹H-NMR (CDCl₃): 0.87 (t over m, 5H), 1.1-1.85 (m, 5H), 2.4 (s,1H),3.78 (t, 2H), 3.85 (s, 1H), 4.25 (t, 2H).

EXAMPLE 6B endo-[2.2.1]bicycloheptyl-2-amino-oxazoline

[0079] The amine from Aldrich (as HCl salt was dissolved in 25% NaOH andextracted 3 times with CH₂Cl₂, dried over Na₂SO₄ and concentrated to awaxy foam, dried under cauum, and treated with choloethylisocyanate aswith the exo amine above in 6A.

[0080] mp 122-124° C.

[0081]¹H-NMR (CDCl₃): 1.08-1.26 (m, 5H), 1.32-1.85 (m, 5H), 2.28 (br.d,1H), 3.45 (s, 1H), 3.79 (t, 2H), 4.24 (t, 2H).

EXAMPLE 7 2-Carbomethoxy-3-ethyl[2.2.1]bicyclo Δ2,3, Δ5,6 heptadiene

[0082] Methyl pent-2-yn-oate (5.3 g, 126.16 mmol) was dissolved intoluene (30 ml) and placed in a sealable tube. To this was added freshlycracked cyclopentadiene. The tube was sealed and placed in a oil bath at168° C. for 42 hours. The excess cyclopentadiene was removed byKugelrohr distillation. The product was isolated in 70.3% yield (5.26g).

EXAMPLE 8 Cis 2-carbomethoxy-3-ethyl[2.2.1]bicycloheptane

[0083] The cycloadduct (6) (5.26 g, 29.5 mmol) was dissolved in MeOH (60ml) and bubbled with Ar, and to the solution was added 10% palladium oncarbon (500 mg). The reaction vessel containing this mixture was put ona Parr apparatus for hydrogenation at 50 psi overnight. The reducedmaterial was filtered through celite and solvent concentrated. Theresidue was dissolved in 1M H₃PO₄ and washed with dichloromethane. Theaqueous layer was basified with 25% NaOH to ca. pH 13. This wasextracted with dichloromethane three times. The organic layers werecombined and concentrated to give product in 81% yield (4.7 g).

EXAMPLE 9 Cis 2(3-ethyl-bicyclo[2.2.1]heptyl)amine

[0084] The ester (3) (2.0 g, 10.2 mmol) was dissolved in a MeOH/THF (30ml/20 ml) solution. This was treated with 2N LiOH (10.2 ml, 20.4 mmol)in H₂O at 100° C. and refluxed. The reaction was concentrated to a pasteand dissolved in 40 ml H₂O and washed twice with dichloromethane. Theorganic layers were combined and concentrated to give the correspondingacid. This acid was dissolved in acetone (20 ml), and triethylamine(3.06 ml, 22.1 mmol) was added dropwise. Next ethylchloroformate wasadded dropwise (2 ml, 20.9 mmol) at 0° C. The reaction was stirred for 1hour. NaN₃ (676 mg, 10.4 mmol) was added in portions at 0° C. for anadditional hour. The reaction was partitioned between ice water anddichloromethane. The organic layers were combined and concentrated togive the acyl azide. This was then treated with benzyl alcohol (995 mg,9.2 mmol) in toluene and refluxed at 110° C. for 30 minutes. Thereaction was washed with H₂O and extracted in dichloromethane.Concentration of solvent gave the benzyl carbamate. The carbamate wasreduced in the same manner as before with 10% palladium on carbon. Theproduct was obtained in an overall yield of 45% (550 mg).

[0085] NMR H¹(CDCl₃): 0.8(t, 3H), 1.0-1.6(m, 9H), 1.8 (s,1H), 2.2(s,1H), 4.7(s,1H), 5.3(s,2H).

EXAMPLE 10A

[0086] Cis 2-(3-ethyl-bicyclo[2.2.1]heptyl)amino-oxazoline

[0087] The bicyclic amine (8) was treated as in the procedure outlinedfor the preparation of the trans compound (5A) above.

[0088]¹H-NMR (CDCl₃): 0.8(t, 3H), 1.00-2.00(m, 9H), 2.1(s,1H),2.5(s,1H), 3.9(s,1H), 3.8(t, 2H), 4.2(t, 2H).

[0089]¹³C NMR (CDCl₃): d 14.5, 20.8, 25.5, 28.2, 38.2, 40.3, 44.7,54.42, 55.05, 64.3, 69.2.

[0090] Analysis calculated for C₁₂H₂₀N₂O: C, 69.09; H, 9.68; N, 13.55;Found: C, 68.6; H, 9.24; N, 13.45.

EXAMPLE 10B Cis 2-(3-ethyl bicyclo[2.2.1]heptyl)aminothiazoline

[0091] can be prepared by substituting the bicyclic amine (8) for (4) inthe preparation of 5B above.

EXAMPLE 10C

[0092] Cis 2-(3-ethyl-bicyclo[2.2.1]heptyl)aminoimidazoline

[0093] Likewise, 9C can be prepared by substituting the bicyclic amine(8) for (4) in the preparation of 5C above.

EXAMPLE 11 2-N-Bornylamino-oxazoline

[0094] To a THF solution of the amine (250 mg, 1.63 mmol) at 0° C. wasadded chloroethylisocyanate (189 mg, 1.79 mmol) dropwise. The reactionwas allowed to warm to r.t. and after stirring for one hr., all startingmaterial was consumed. The reaction mixture was poured into 1M H3PO4 andextracted three times with methylene chloride. After drying, thesolution was concentrated and the resulting solid was warmed in aqueousmethanolic NaHCO3. The reaction was extracted from 0.5N NaOH and dried(Na2SO4), concentrated and chromatographed over 250-400 mesh silicausing 5% ammonia saturated methanol in CH₂Cl₂ as eluent. Yield: 206 mg(60%).

[0095]¹³C NMR (CDCl₃) 161.7, 67.6, 57.8, 52.9, 49.2, 48.0, 44.8, 38.4,28.3, 27.6, 19.9, 18.7, 13.7.

[0096]¹H NMR (CDCl₃) 4.24 (2H, m); 3.80 (3H, m); 2.38 (1H, m); 1.87-1.1(6H, env, m); 0.93 (3H, s); 0.87 (3H, s); 0.86 (3H, s).

EXAMPLE 12 Bicyclo[2.2.2]octane aminooxazoline Adamantylaminooxazoline

[0097] In a similar manner to Example 10, commercially availablebicyclo[2.2.2]octane amine and adamantylamine can be used to prepare the2-bicyclo[2.2.2]octane-aminooxazoline and adamantylaminooxazolinecompounds, respectively.

EXAMPLE 13 Receptor Binding Assays

[0098] 13 A.

[0099] Tissue preparation: Membrane suspensions were prepared from humancerebral cortex (HCC) obtained from the UCI Organ and Tissue Bank andrat kidney cortex (RKC). Briefly, tissues (1 g) were homogenized in 25ml of iced-cold 5 mM tris, pH 7.4 with a Polytron homogenizer for 30secs at setting #7, and centrifuged for 10-12 minutes at 300×g at 4° C.The supernatant was filtered through 2 layers of gauze and diluted 1:2with 50 mM Tris-HCl buffer, pH 7.4, then centrifuged at 49,000×g for 20minutes. The pellet fraction was washed 3 times (resuspended in Tris-HClbuffer and centrifuged for 20 minutes at 49,000×g). The pellet was thenstored at −80° C. until the binding assay.

[0100] Cell preparation: HT-29 and chinese hamster ovary (CHO) cellsexpressing the human α_(2A) (CHO-C10) receptor and CHO cells (CHO-RNG)expressing the rat α_(2B) adrenoceptor were grown to near confluency inDulbecco's modified Eagle's medium supplemented with 10% fetal bovineserum using standard cell culture methods. Cells were harvested byscraping and placed into cold buffer of the following composition: 50 mMTris-HCl, 5 mM EDTA, pH 7.4). Cells were then homogenized with aPolytron homogenizer for 2×10 secs at setting #7, and centrifuged for 20minutes at 49,000×g. The pellet fraction was washed (resuspended inTris-HCl, pH 8 buffer and centrifuged for 15-20 minutes at 49,000×g) 2times and stored at −100° C. until binding assay.

[0101] Binding studies: The radioligands [³H]rauwolscine (specificactivity 80 Ci/mmol) and [³H]prazosin (specific activity 76 Ci/mmol)were obtained from New England Nuclear, Boston, Mass. Frozen membranepellet was resuspended in 25 mM glycine/glycine, pH 7.4 and incubatedwith radioligand under the following conditions: CHO-C10, CHO-RNG,HT-29-[³H]rauwolscine, 22° C., 30 minutes; RKC-[³H]rauwolscine, 0° C.,120 minutes; and, HCC-[³H]prazosin, 22° C., 30 minutes in a final volumeof 500 μl. At the end of the incubation period, the samples werefiltered through glass fiber filters (Whatman GF/B) in a 96 well cellharvester and rapidly washed four times with 4 ml of ice-cold 50 mMTris-HCl buffer. The filters were then oven dried and transferred toscintillation vials containing 5 ml of Beckman's Ready Protein®scintillation cocktail for counting. Specific binding defined by 10 μMphentolamine for competition studies were as follows: 0.3 nM[³H]rauwolscine-CHO-C10 99%; 0.4 nM [³H]rauwolscine-CHO-RNG 99%; 0.7 nM[³H]rauwolscine-HT-29 90%; 1 nM [³H]rauwolscine-RKC 92%, and 0.3 nM[³H]prazosin-HCC 87%. Protein concentrations were determined with aprotein assay kit from Bio Rad. Binding isotherms, equilibriumdissociation and affinity constants were analyzed and determined by thenon-linear least squares curve fitting programs AccuFitCompetition/Saturation by Beckman.

[0102] Binding studies: The radioligands [³H]rauwolscine (specificactivity 80 Ci/mmol), [³H]prazosin (specific activity 76 Ci/mmol) and[³H]brimonidine (UK-14,304; specific activity 63 Ci/mmol) were obtainedfrom New England Nuclear, Boston, Mass. Frozen membrane pellet wasresuspended in either 50 mM tris, 2 mM EGTA, 1 mM MgCl₂, pH 7.5 (RbKC,RbICB-[³H]brimonidine); 50 mM tris, 0.5 mM EDTA, 5 mM NaCl, pH 7.7(RbICB-[³H]rauwolscine); 25 mM glycine/glycine, pH 7.4 (RtKC, CHO-C10,CHO-RNG, HT-29, HCC) or 50 mM tris, 0.1 mM MnCl₂, pH 7.7 (RtCC).Membrane protein homogenate (75-200 μg) was incubated with radioligandunder the following conditions: RbKC and RbICB-[³H]rauwolscine, 22° C.,45 minutes; RtCC and RbICB-[³H]brimondine, 22° C., 90 minutes; CHO-C10,CHO-RNG and HT-29-[³H]rauwolscine, 22° C., 30 minutes; HCC-[³H]prazosin,22° C., 30 minutes; and, in a final volume of 250 or 500 μl. At the endof the incubation period, the samples were filtered through glass fiberfilters (Whatman GF/B) in a 24 or 96 well cell harvester and rapidlywashed four times with 4 mls of iced-cold 50 mM Tris-HCl buffer. Thefilters were then oven dried and transferred to scintillation vialscontaining 10 mls of Beckman's Ready Protein® scintillation cocktail forcounting. Specific binding defined by 10 μM phentolamine for competitionstudies were as follows: 2.4 nM [³H]brimonidine-RbICB 62%; 2.4 nM[³H]rauwolscine-RbICB 75%; 2 nM [³H]rauwolscine-RbKC 88%; 0.3 nM[³H]rauwolscine-CHO-C10 99%; 0.4 nM [³H]rauwolscine-CHO-RNG 99%, 0.3 nM[³H]prazosin 87%; and 1 nM [³H]rauwolscine-RtCC 90%. Proteinconcentrations were determined with a protein assay kit from Bio Rad.Binding isotherms, equilibrium dissociation and affinity constants wereanalyzed and determined by the non-linear least squares curve fittingprograms EBDA (BioSoft) or AccuFit Competition/Saturation by Beckman.

[0103] 13 B.

[0104] Cell preparation: Chinese hamster ovary (CHO) cells expressingthe human α_(2A) (CHO-C10) and the rat α_(2B) (CHO-RNG) adrenoceptorswere grown to near confluency in Dulbecco's modified Eagle's mediumsupplemented with 10% fetal bovine serum using standard cell culturemethods. Cells were harvested by scraping and placed into cold buffer ofthe following composition: 50 mM Tris-HCl, 5 mM EDTA, pH 7.4). Cellswere then homogenized with a Polytron homogenizer for 2×10 secs atsetting #7, and centrifuged for 20 minutes at 49,000×g. The pelletfraction was washed (resuspended in Tris-HCl, pH 8 buffer andcentrifuged for 15-20 minutes at 49,000×g) 2 times and stored at −100°C. until binding assay.

[0105] 13C.

[0106] Binding Studies: Determination of K_(i)

[0107] The radioligands [³H]rauwolscine (specific activity 80 Ci/mmol)and [³H]prazosin (specific activity 76 Ci/mmol) were obtained from NewEngland Nuclear, Boston, Mass. Frozen membrane pellet was resuspended in25 mM glycine/glycine, pH 7.4 and incubated with radioligand under thefollowing conditions: CHO-C10, CHO-RNG-[³H]rauwolscine, 22° C., 30minutes; and, HCC-[3H]prazosin, 22° C., 30 minutes in a final volume of500 ul. At the end of the incubation period, the samples were filteredthrough glass fiber filters (Whatman GF/B) in a 96 well cell harvesterand rapidly washed four times with 4 mls of iced-cold 50 mM Tris-HClbuffer. The filters were then oven dried and transferred toscintillation vials containing 5 ml of Beckman's Ready Protein®scintillation cocktail for counting. Specific binding defined by 10 μMphentolamine for competition studies were as follows: 0.3 nM[³H]rauwolscine-CHO-C10 99%; 0.4 nM [³H]rauwolscine-CHO-RNG 99%, and 0.3nM [³H]prazosin-HCC 87%. Protein concentrations were determined with aprotein assay kit from Bio Rad. Binding isotherms, equilibriumdissociation and affinity constants were analyzed and determined by thenon-linear least squares curve fitting programs AccuFitCompetition/Saturation by Beckman.

[0108] Determination of α₂ Activation: Measuring Efficacy (EC₅₀)

[0109] Vas Deferens: The prostatic ends of the vas deferens (2-3 cm)were removed from albino rabbits and mounted between platinum electrodesin 9 ml organ baths containing Krebs-Hensleit solution of the followingcomposition (mM): NaCl 119, KCl 4.7, MgSO₄ 1.5, KH₂PO₄ 1.2. CaCl₂ 2.5,NaHCO₃ 25 and glucose 11. This solution was maintained at 35° C. andbubbled with 95% O₂ and 5% CO₂. The tissue was equilibrated at 0.5 gtension for 30 minutes. The vas deferens strips were then fieldstimulated at 0.1 Hz, 2 msec, 90 mA using a square wave stimulator(World Precision Instruments A310 Accupulser/A385 Stimulus Isolater), ora Grass S48 stimulator at 0.1 Hz, 2 msec, 70 volts. After 30 minutes ofelectrical stimulation, cumulative concentration-response curves in 0.25log units were obtained with a 4 minute contact time for eachconcentration. Each tissue was used to evaluate only one drug. Tissuecontractions produced by the field stimulation were measuredisometrically using Grass FT-.03 force-displacement transducers andrecorded on a Grass Model 7D physiograph. The reduction inelectrically-evoked peak height by the drugs was measured and expressedas a percentage of the pre-drug peak height. The IC₅₀ was determined asthe concentration which produced a 50% reduction in peak height. TABLE IK_(i) (nM) Structure α_(2A)(CHO-C10) α_(2B)(CHO-RNG) EC₅₀ (nM) tested α₁(HT-29)* (RKC)^(†) α₂ (vas def.)

11,131  1,751  4,174 >56,200

1,864    3.1    7.8  29,000

6.730    14.3    72 >56,200

10,977  6,571  6,103 not tested as no binding was observed

73    1.9    27  3,700

1,860    1.1    4.6 >56,000

>100,000   150*   317^(†)  1,100

24,760    59   616 not tested

>100,000 67,247 57,075 not tested as no binding observed

>10,000    43*    58^(†) not tested

>100,000 23,320 20,950 not tested

8,600    25   256    903

8,851    9.8    28.1  46,000

1,600    0.6    8.3     1.0

5,824    29*    59^(†) not tested

42,000    58*   167^(†) not tested

17,240   288*  5,100^(†) not tested

>10,000    4.2    11.5 >10,000

>10,000   368  1,935  16,000

32,487   119   770 >10,000

>10,000   102   358  >5,000

34,950   352  1,838 >10,000

What is claimed is:
 1. A compound of formula I

in which: ring A is one of the five alternative multi-cyclic rings asshown wherein a dotted line adjacent to a bond indicates that a singlebond or a double bond may be present at that position; X is nitrogen,oxygen or sulfur; R is hydrogen, straight or branched chain alkyl of 1to 6 carbon atoms, or straight or branched chain alkenyl of 2 to 6carbon atoms, a cycloaliphatic ring of 3 to 6 carbon atoms, phenyloptionally mono- or di-substituted with hydroxy, halogen, alkyl of 1 to3 carbon atoms or alkoxy of 1 to 2 carbon atoms, ormethylenedioxyphenyl; or a stereoisomer, or a pharmaceuticallyacceptable salt thereof.
 2. The compound of claim 1 wherein X is oxygen.3. The compound of claim 1 wherein X is nitrogen.
 4. The compound ofclaim 1 wherein X is sulfur.
 5. The compound of claim 1 wherein the ringA is bicyclo[2.2.1]heptane (norbornane).
 6. The compound of claim 2wherein the ring A is bicyclo[2.2.1]heptane (norbornane).
 7. Thecompound of claim 5 wherein R is hydrogen; phenyl optionally mono- ordi-substituted with hydroxy, halogen, alkyl of 1 to 3 carbon atoms oralkoxy of 1 to 2 carbon atoms; or methylenedioxyphenyl.
 8. The compoundof claim 1 which istrans-2-(3-phenyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline.
 9. Thecompound of claim 1 which istrans-2-(3-phenyl-bicyclo[2.2.1]heptyl)-2-aminoimidazoline.
 10. Thecompound of claim 1 which istrans-2-(3-methylenedioxy-phenyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline.11. The compound of claim 1 which istrans-2-(3-propyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline.
 12. Thecompound of claim 1 which isexo-2-(bicyclo[2.2.1]heptyl)-2-aminooxazoline.
 13. A compositionsuitable for administration to a mammal having a disease state which isalleviated by treatment with an α₂-blocking agent, the compositioncomprising a therapeutically effective amount of a compound of formula I

in which: ring A is one of the five alternative multi-cyclic rings asshown wherein a dotted line adjacent to a bond indicates that a singlebond or a double bond may be present at that position; X is nitrogen,oxygen or sulfur; R is hydrogen, straight or branched chain alkyl of 1to 6 carbon atoms, or straight or branched chain alkenyl of 2 to 6carbon atoms, a cycloaliphatic ring of 3 to 6 carbon atoms, phenyloptionally mono- or di-substituted with hydroxy, halogen, alkyl of 1 to3 carbon atoms or alkoxy of 1 to 2 carbon atoms, ormethylenedioxyphenyl; or a stereoisomer, or a pharmaceuticallyacceptable salt thereof, in admixture with one or more pharmaceuticallyacceptable carriers.
 14. The composition of claim 13 wherein thetherapeutically effective compound is selected from the group consistingof trans-2-(3-phenyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline,trans-2-(3-phenyl-bicyclo[2.2.1]heptyl)-2-aminoimidazoline,cis-2-(3-phenyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline,trans-2-(3-methylenedioxy-phenyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline,trans-2-(3-propyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline,cis-2-(3-propyl-bicyclo[2.2.1]heptyl)-2-aminooxazoline andexo-2-(bicyclo[2.2.1]heptyl)-2-aminooxazoline.
 15. A method for treatinga mammal having a disease state which is alleviated by treatment with anα₂ blocking agent, which comprises administering a therapeuticallyeffective amount of a compound of the formula I

in which: ring A is one of the five alternative multi-cyclic rings asshown wherein a dotted line adjacent to a bond indicates that a singlebond or a double bond may be present at that position; X is nitrogen,oxygen or sulfur; R is hydrogen, straight or branched chain alkyl of 1to 6 carbon atoms, or straight or branched chain alkenyl of 2 to 6carbon atoms, a cycloaliphatic ring of 3 to 6 carbon atoms, phenyloption ally mono- or di-substituted with hydroxy, halogen, alkyl of 1 to3 carbon atoms or alkoxy of 1 to 2 carbon atoms, ormethylenedioxyphenyl; or a stereoisomer or a pharmaceutically acceptablesalt thereof.
 16. The method of claim 15 wherein said disease state iselevated intraocular pressure.
 17. The method of claim 15 wherein saiddisease state is depression.
 18. The method of claim 15 wherein saiddisease state is non insulin-dependent diabetes.
 19. The method of claim15 wherein said disease state is male impotence.
 20. The method of claim9 wherein said disease state is obesity.